golang常用测力

常用


package main

import (
    "context"
    "fmt"
    "go.mongodb.org/mongo-driver/bson"
    "hugo/mon"
    "hugo/publishtask"
    "strconv"
    "sync"
    "sync/atomic"
    "time"
)

type Abs struct {
    UserName string `bson:"username"`
    Email string `bson:"email"`
}


func b()(i int,err error){
    if err := fmt.Errorf("aaaa");err!=nil{
        fmt.Println(err,232323)
    }
    fmt.Println(err,8888)
    return
}

func main(){
    publishtask.CreateUser()
    return

    abs := new(Abs)
    fmt.Println(time.Now().Format("2006-01-02 15:04:05"))
    fmt.Println(time.Now().Second())

    singResult :=mon.Client.Collection("tbl_data").FindOne(context.TODO(),bson.M{"username":"胡工827"})
    singResult.Decode(abs)
    fmt.Println(time.Now().Format("2006-01-02 15:04:05"))
    fmt.Println(time.Now().Second())
    return

    wg := new(sync.WaitGroup)
    for i := 0; i < 100; i++ {
        wg.Add(1)
        go insertMon(wg)
    }
    wg.Wait()

    fmt.Println(time.Now().Format("2006-01-02 15:04:05"))

}

func insertMon(wg *sync.WaitGroup){

    defer func() {
        wg.Done()
    }()

    data := Abs{"hugo","136586551@163.com"}

    for i := 1; i < 100000; i++ {
        iStr := strconv.Itoa(i)
        data.UserName = fmt.Sprintf("胡工%s",iStr)
        insertRes,err:=mon.Client.Collection("tbl_data").InsertOne(context.TODO(),data)
        if err != nil {
            fmt.Println(err,insertRes)
        }
    }

}

func doSth(){
    //ctx,cancel :=context.WithTimeout(context.Background(),time.Duration(150)* time.Microsecond)
    timer := time.NewTimer(2*time.Second)

    //go sth(ctx)

    for range timer.C{
        fmt.Println(time.Now().Format("2006-01-02 15:04:05"))
    }

    return
    for {
        select{
        case <-timer.C:
            fmt.Println("定时器时间到了,开始要取消cancel()\n")
            //cancel()
            return
        default:
            //fmt.Println("还没有开始123")

        }
    }

}

func sth(ctx context.Context){
    fmt.Println(1111)
    for{
        time.Sleep(time.Microsecond * 100)
        select {
        case <-ctx.Done():
            fmt.Println("取消结束了")
            return
        default:
            fmt.Println("还没有被结束567")
        }
    }
}

//定时器每隔2秒执行一次代码块
func timer1(){
    timer := time.NewTimer(2*time.Second)
    for range timer.C{
        fmt.Println(time.Now().Format("2006-01-02 15:04:05"))
    }
}

//定时器隔2秒执行一次代码块,仅仅执行一次
func timer2(){
    timer := time.NewTimer(2*time.Second)
    i :=0
    for true {
        select{
        case <-timer.C:
            fmt.Println("定时器执行了")
        default:
            if i == 0 {
                fmt.Println("定时器还没执行了333333")
            }
        }
        i++
    }
}

//context 执行
//for 里面的break  会直接终止for循坏
//select 里面的case里面的break是终止case里面的代码块执行,不会终止到select外层的for
//select 里面不用break也只会执行一个case
func context1(){
    ctx,cancel :=context.WithTimeout(context.Background(),2 * time.Second)
    i:=0

    go func(ctx context.Context) {
        for{

            select{
                case <-time.After(10 * time.Nanosecond):
                    fmt.Println("时间1")
                    fmt.Println("78787878")

                case <-ctx.Done():
                    fmt.Println("取消的命令来了")
                    return
                default:
                    if i == 0 {
                        fmt.Println("11122333")
                    }
                    break
            }
            i++
        }
    }(ctx)

    time.Sleep(1 * time.Second)
    fmt.Println("cancel来取消的")
    cancel()

}

//执行到的switch的case如果有 fallthrough  就会在不判断的情况下直接执行下一个case
func switch1(){
    df :=1
    switch df{
    case 1:
        fmt.Println(11)
        fallthrough
    case 2,3,4:
        fmt.Println(222)
        fallthrough
    case 22,32,42:
        fmt.Println(8989)
    case 222,322,422:
        fmt.Println(84378434)

    }
}
type Mutex struct {
    key  int32
    sema uint32
}

//sync.lock,sync.Rlock,
//Lock会让 Lock,Rlock等待,也就是锁住的意思
//Rlock会让 lock等待,但是不会让Rlock等待
func lock1(){
    m := new(sync.RWMutex)

    // 多个同时读
    go lockRead(1,m)
    go lockRead(2,m)
    time.Sleep(1*time.Second)

    go lockRead3(3,m)

    time.Sleep(15*time.Second)
}
func lockRead(i int,m *sync.RWMutex) {
    println(i,"read start")

    m.RLock()
    println(i,"reading")
    time.Sleep(5*time.Second)
    m.RUnlock()

    println(i,"read over")
}
func lockRead3(i int,m *sync.RWMutex) {
    println(i,"read3 start")

    m.Lock()
    println(i,"read3ing")
    time.Sleep(1*time.Second)
    m.Unlock()

    println(i,"read3 over")
}


//后面sync.atomic
//加锁是一种悲观策略。原来所有锁的底层又跑到操作系统那里去了,想想也是琐是用来锁住多线程的,线程上游是进程,进程上游是操作系统,最终交汇点进程无疑
//操作系统的锁策略是时间换空间的策略,从而保证数据安全
//无锁策略,利用到了cps算法,并没有惊动到操作系统那一层,让各线程自身就具备鉴别是否资源已经被抢占,https://blog.csdn.net/yanluandai1985/article/details/82686486
func atomic1(){
    m := int32(0)
    wg := new(sync.WaitGroup)
    for i := 1; i < 1000; i++ {
        wg.Add(1)

        go func() {
            if d :=atomic.AddInt32(&m,1);d==1{
                //fmt.Println(123)
            }else{
                //fmt.Println(d,222)
            }

            wg.Done()
        }()
    }
    wg.Wait()

    fmt.Println(m)



}



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